Embolectomy devices and methods for treatment of acute ischemic stroke condition

ABSTRACT

Clot engagement element comprising bundle of unwoven fibers can be assembled to form an acute stroke treatment device. The device has the capability of forming a three dimensional filtration matrix comprising effective pores with a distribution of sizes. The bundle of fiber design allows the device to be effectively delivered into circuitous cerebral arteries to remove clot that causes stroke. The fiber bundle based filtration matrix offers the advantages of conforming to the changing inner perimeter of a blood vessel during a clot removal process and thus the capability to effectively retain and remove a clot in the vessel. The filtration matrix offers the additional advantage to trap any break-off of the clot during the removal process. A plurality of fiber bundles can be combined to form an effective clot engagement element. Supplemental engagement structure as well as mechanical treatment structure can be integrated into the stroke treatment device. The deployment of the fiber based elements can be facilitated by actuation tool. Aspiration can be employed during the clot removal process.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. provisional patent applicationSer. No. 61/323,461 filed on Apr. 13, 2010 to Jason Galdonik et al.,entitled “Embolectomy devices and methods for treatment of acuteischemic stroke condition,” incorporated herein by reference.

FIELD OF THE INVENTION

The inventions, in general, are related to acute stroke treatmentdevices used to remove clot in cerebral arteries. The inventions arefurther related to the method of using and making of such devices.

BACKGROUND

Ischemic strokes can be caused by clots within a cerebral artery. Theclots block blood flow, and the blocked blood flow can deprive braintissue of its blood supply. The clots can be thrombus that forms locallyor an embolus that migrated from another location to the place of vesselobstruction. To reduce the effects of the cut off in blood supply to thetissue, time is an important factor. In particular, it is desirable torestore blood flow in as short of a period of time as possible. Thecerebral artery system is a highly branched system of blood vesselsconnected to the interior carotid arteries. The cerebral arteries arealso very circuitous. Medical treatment devices should be able tonavigate along the circuitous route posed by the cerebral arteries forplacement into the cerebral arteries.

SUMMARY OF THE INVENTION

In a first aspect, the invention pertains to an acute stroke treatmentdevice comprising one or more flexible delivery wires and a fiber-basedclot engagement element that comprises at least one bundle of unwovenfibers and a first attachment element wherein each fiber of the bundleis secured at one end to the first attachment element. The firstattachment element either comprises a slide that can translate over thedelivery wire or an anchor that is secured at a fixed position aroundthe circumference of the delivery wire. In some embodiments, if thefirst attachment element has an anchor fixed to the delivery wire, theother end of the fibers are unsecured or are secured in a bundle at asecond attachment element without fixed attachment to an actuationstructure, and the bundle of fibers have a first low profile deliveryconfiguration and a second configuration with a portion of the fibersthat is unsecured flaring outward relative to the delivery wire to havedimensions suitable for conform to the changing inner perimeter of ablood vessel and the fibers do not spontaneously transition between thefirst configuration and the second configuration.

In another aspect, the invention pertains to method for the delivery ofa clot engagement device within a cerebral artery in which the methodcomprises the steps of positioning a distal opening of a guide catheterinside an interior carotid artery, delivering the clot engagement devicethrough the guide catheter to access a cerebral artery downstream fromthe interior carotid artery, and advancing an actuation element over theflexible wire to deploy the fiber-based element to an extendedconfiguration with the fibers conforming to the inner perimeter of thearteries. In general, the clot engagement device comprises a fiber-basedclot engagement element supported by a flexible wire. Also, the movementof the actuation element can be unconstrained over the flexible wire.

In a further aspect, the invention pertains to method for the removal ofa blood clot from a cerebral artery causing an acute stroke event, themethod comprising the steps of positioning of a fiber-based clotengagement device inside the cerebral artery distal to the blood clot ona delivery wire, deploying the fiber-based clot engagement device to anextended configuration with at least a portion of the fibers extendingoutward relative to the delivery wire to conform to the inner perimeterof the cerebral artery, pulling the deployed clot engagement devicetowards an aspiration catheter positioned inside an interior carotidartery so the clot engagement device becomes engaged with the clot, andapplying aspiration through the aspiration catheter while drawing theclot into the aspiration catheter with proximal movement of the clotengagement device. In some embodiments, the fibers of the clotengagement device remain conforming to the changing inner perimeter ofthe arteries and thereby remain engaging the clot during the pullingprocess.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1( a) is a side perspective view of a fiber cartridge with a bundleof fibers having a single fixed end.

FIG. 1( b) is a side perspective view of a fiber cartridge with a bundleof fibers having both ends fixed.

FIG. 1( c) is a side perspective view of the fiber cartridge of FIG. 1(a) with the non-secured end of the fibers flare outward in an extendeddeployed configuration.

FIG. 1( d) is a side perspective view of the fiber cartridge of FIG. 1(b) with the non-constrained middle portion of the fibers flare outwardin an extended deployed configuration.

FIG. 2( a) is a fragmentary side perspective view of a filter elementfixed to a delivery wire protruding outside a microcatheter.

FIG. 2( b) is a fragmentary side view of a delivery wire with a stop anda slidable filter element engaging the stop.

FIG. 2( c) is a fragmentary side view of a plurality of filter cartridgebundles in a combination advanced out of a microcatheter along aflexible wire.

FIG. 3( a) is a fragmentary side view of a deployed fiber-based filterelement that is maintained in the deployed configuration due to theinteraction of the fiber bundle with a microcatheter.

FIG. 3( b) is a fragmentary side view of a push catheter with a slotteddistal end helps to deploy a filter element extended out of the pushcatheter.

FIG. 4( a) is a perspective side view of a clot engagement element witha fiber bundle covered with an exterior slotted heat shrink jacketassembled in a cartridge that can slide over a flexible wire fordelivery to a treatment location.

FIG. 4( b) is a perspective side view of the device of FIG. 4( a) in adeployed configuration.

FIG. 5( a) is a photograph of a filter element comprising multiple fibercartridges covered with heat shrink jacket in a narrow profile deliveryconfiguration.

FIG. 5( b) is a photograph of the device of FIG. 5( a) in a deployedconfiguration.

FIG. 6( a) is a fragmentary side view of a filter element comprisingmultiple free ended fiber cartridges with a fiber tail that slide alongthe delivery wire in a narrow profile delivery configuration.

FIG. 6( b) is a fragmentary side view of the device of FIG. 6( a) in apartially deployed or extended configuration.

FIG. 7( a) is a photograph of a push catheter with a filament cartridgeas a deployment tool in a deployed configuration.

FIGS. 7( a 1)-(a 3) are schematic diagrams of various version of thepush catheter with different deployment tools.

FIG. 7( b) is a fragmentary side view of the push catheter with thefilament cartridge of FIG. 7( a) in combination with a filter element ina narrow profile delivery configuration.

FIG. 7( c) is a schematic diagram showing the device of FIG. 7( b) in anarrow profile delivery configuration with the push catheter and thefilament cartridge inside a microcatheter and the filter elementextended outside the microcatheter with the insert showing analternative embodiment of the push catheter with an open wovenstructure.

FIG. 7( d) is a schematic diagram showing the device of FIG. 7( c) withthe filament cartridge advanced outside of the microcatheter in adeployed extended configuration.

FIG. 7( e) is a schematic diagram showing the device of FIG. 7( d) withthe push catheter and the extended filament cartridge helping to deploythe filter element into an extended configuration.

FIG. 8 is a fragmentary side view of a filter element coupled with afilament supplemental engagement structure.

FIG. 9( a) is a fragmentary side view of a filter element in a reduceddiameter delivery configuration coupled with a Nitinol framesupplemental engagement structure.

FIG. 9( b) is a fragmentary side view of the device of FIG. 9( a) withthe filter element in a deployed configuration.

FIG. 9( c) is a fragmentary side view of an alternative Nitinol framesupplemental engagement structure with coiled Nitinol filaments uponrelease.

FIG. 10 is a fragmentary side view of the proximal end of a clotengagement system with appropriate fittings.

FIGS. 11( a)-(d) illustrates a process of a clot or emboli removal usingan embodiment of the treatment device described herein.

FIGS. 12( a)-(d) illustrates a process of a clot or emboli removal usingan embodiment of the treatment device that has an angioplasty balloon.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Improved cerebral embolectomy devices have been designed that cannavigate through the circuitous paths of the cerebral arteries to a clotand to pass the clot with a fiber-based clot engagement element. Toallow for the devices to navigate the circuitous path, the devices arebased on a flexible wire that engages with fiber-based elements. Aseparate deployment device is used to track over the flexible wire afterthe distal end of the device is positioned past the clot to deploy thefiber based elements into an extended position, which may conform to thevessel wall around its inner perimeter. Embolectomy procedures for thetreatment of acute stroke conditions involve navigating the cerebralembolectomy device along the tortuous path of cerebral arteries suchthat the device is positioned distal to the clot or emboli. The deviceis then deployed to pull the clot or emboli to a retrieval catheter,which can be an aspiration catheter. In some embodiments, the retrievalcatheter has its distal end in the interior carotid artery. The cerebralembolectomy device generally comprises fibers that are designed forextending radially outward to contact the walls of the vessel to form amatrix. In some embodiments, the fiber matrix is designed to maintaincontact with the vessel walls as the clot is pushed through the vesselswith the vessels naturally undergoing significant increase in the vesselinner diameter if pushed a significant distance relative to the vesselstructure.

Due to the circuitous nature of the cerebral arteries, the devicesintended for placement up the cerebral arteries are designed for a highdegree of flexibility and maneuverability. The fiber structuresgenerally have a lower profile initial configuration and a largerprofile extended configuration. The fiber structure can be supplementedwith an element having a greater mechanical strength to facilitate thedislodgement of the clot. This supplemental structural element can beformed from wire and/or a thicker fiber. In additional or alternativeembodiments, mechanical treatment devices, such as balloon or stents canbe delivered over a flexible wire supporting the fiber-based structureto facilitate removal of the clot. Suction generally is applied throughthe retrieval catheter to facilitate removal of the clot from thevessel. The improved devices and corresponding procedures are designedfor a high success rate with a low risk of losing portions of the clotas emboli can migrate downstream.

To reduce the clinical effects of a clot within a cerebral artery, theclot can be removed, and it is correspondingly desirable to keep thetime for removal short. For convenience, as used herein all arteriesdownstream from the interior carotid arteries are referred to as acerebral artery. The process of removal of the clot poses the challengeof tracking a device to the clot and physically engaging the clot toremove it. For at least a portion of the removal process, the clot canbe drawn into a catheter or sheath to facilitate retention of the clot.Any portions of the clot that remains in the vessel or breaks off fromthe original clot can eventually flow downstream to block a smallervessel with associated harm to the patient. The placement of a cerebralembolectomy device within a cerebral artery poses significant challengesdue to the circuitous path through the vessels.

Fiber based devices have been found to result in surprisingly effectivefiltering within blood vessels. These devices can comprise a fiber matformed of the fibers in a deployed configuration such that the fiber mathas the structure of a three dimensional filtration matrix. The threedimensional filtration matrix comprises effective pores with adistribution of sizes within the matrix. The pores with various sizesinside the matrix provide complex flow passages through the fiber mat toallow blood to pass through while effective retain emboli of varioussizes. In some embodiments, the fibers are configured to be a non-wovenbundle. Even after the deployment and formation of the fiber mat, thefibers remain unwoven. Filters formed from fiber bundles are describedfurther in U.S. Pat. No. 7,879,062 to Galdonik et al., entitled “FiberBased Embolism Protection Device,” incorporated herein by reference.

In some embodiments, it can be desirable for a deployed fiber-basedelement(s) within a device to block the flow of a substantial majorityof particulates with a diameter of at least about 0.2 mm while allowingthe flow of a substantial majority of particulates with a diameter of nomore than about 0.001 mm, and in other embodiments, to block the flow ofa substantial majority of particulates with a diameter of at least about0.1 mm while allowing the flow of a substantial majority of particulateswith a diameter of no more than about 0.01 mm. A substantial majority ofparticulates can be considered to be at least about 90 percent and infurther embodiments at least about 95 percent of all the particulatesflown through. A person of ordinary skill in the art will recognize thatadditional ranges of filtering ability within the explicit ranges arecontemplated and are within the present disclosure.

As discussed in further details below, with proper designs, thefiber-based filter elements can be very effective at trapping emboligenerated during a procedure within a vessel while maintaining flowsubstantially unchanged through the filter. It has been found that in amodified form, fiber-based structures can be used effectively ascerebral embolectomy devices. The extended fibers can engage the clotand assist in the removal of the clot. The filtration character canprovide advantageously the ability to capture any significant fragmentsof the clot, and the surface of the radially extended fiber element canprovide an effective surface for pushing the clot. The fiber-basedfilter element can be further supported with struts and/or with asupplemental engagement structure that facilitates movement of the clot.A supplemental engagement structure can be integrally constructed withthe fiber-based filter device or separately delivered over the wiresupporting the filter device. A supplemental engagement structure mayalso provide for deployment of the fiber based structures to an extendedfiltering configuration. An aspiration catheter can be used tofacilitate removal of the clot and the device while reducing the risk oflosing significant fragments of the clot within the blood vessels.

In some embodiments of improved stroke directed embolectomy proceduresdescribed herein, the clot is first crossed. For example, the clot canbe crossed directly with a filter device. In other embodiments, the clotcan be crossed with a microcatheter, which then provides for thedelivery of the filter device through the microcatheter. If desired, aguidewire can be first used to cross the clot where the guidewire hassuitable flexibility for placement within a cerebral artery. Amicrocatheter can then be advanced over the guidewire and past the clot.Following removal of the guidewire, the lumen of the microcatheterprovides a passage for the delivery of a fiber-based cerebralembolectomy device.

Following the delivery of the cerebral embolectomy device past the clot,the microcatheter may be withdrawn. After deployment of the cerebralembolectomy device, the device can be used to pull the clot from itsresting point in a proximal direction. In some embodiments, the clot ispulled a significant distance such that the clot is out of the cerebralarteries and in an interior carotid artery. If the clot is pulled to theinterior carotid artery, the clot may be pulled past one or morebranches in the vasculature. The vessel diameter can increasesignificantly over the range in which the clot is pulled.

In additional or alternative embodiments, after the microcatheter isremoved, an angioplasty balloon, stent delivery device, atherectomydevice, or other mechanical treatment device for contributing to openingthe vessel can be tracked to the clot over the guidewire. Suchmechanical treatment devices are known in the art. The mechanicaltreatment device can be then used to mechanically engage the clot todisrupt the clot. The fiber-based filter device can be deployeddownstream from the clot to trap any debris that may be generated fromthe clot. After use, the mechanical treatment device can be removed fromthe artery. Then, the clot and/or fragments thereof are removed usingthe fiber-based filter device along with appropriate suction. As withother embodiments, a supplemental engagement structure can also be usedto facilitate removal of the clot and/or clot fragments.

In general, the filter element is designed to fill the vessel diameterto the vessel walls with the fiber matrix contacting or conforming tothe wall of the vessel around the inner perimeter of the vessel. Thefilter element is generally delivered to the clot in a low profileconfiguration and transitioned to an extended configuration comprising afiltration matrix that can contact or conform to the vessel walls aroundthe inner perimeter of the vessel. A fiber mat of the extended non-wovenfibers forms a filtration matrix for blood to flow past the device. Theproperties of the filtration matrix can be adjusted as desired within arange of reasonable parameters. In some embodiments, the fiber mat isresilient so that the fiber mat continues to contact the vessel wallalong the changing inner perimeters of a vessel while the clot is movedwithin the vessel toward a catheter used to remove the clot. At somepoint prior to removal of the clot from the patient, the clot is broughtwithin a catheter for the remainder of the distance out from the body.The filter element or a portion thereof can be similarly brought intothe catheter at its distal end to complete its removal from the patient.Aspiration can be supplied through the catheter to facilitate removal ofthe clot and fragments of the clot, which may or may not be associatedwith the filter element.

A supplemental engagement structure can be similarly delivered in a lowprofile configuration and extended after being placed at an appropriateposition in the vessel. The engagement structure can be constructed frommetal wire, such as a shape memory metal, or with higher gauge polymerfilaments. Suitable shape memory metal includes, for example, cobaltalloys, such as Elgiloy®, a cobalt-chromium-nickel alloy, MP35N, anickel-cobalt-chromium-molybdenum alloy, Nitinol®, a nickel-titaniumalloy, and combinations thereof. The shape memory metals can bestraightened for delivery such that they resume an extendedconfiguration upon release within the vessel. The heavier gauge polymerfilaments and metal wires generally are delivered in smaller number suchthat their bundle or configuration is thin enough for delivery through amicrocatheter. The smaller number of polymer filaments or the metalwires may not form a reasonable filtration matrix and may or may notextend outward to the vessel wall to fill the vessel lumen, but thesupplemental engagement structure can provide greater mechanicalstrength for moving the clot, while providing suitable flexibility fordelivery into a cerebral artery. In some embodiments a combination ofpolymer filaments and metal wires are used. In general, throughout thedescription herein, the term filaments refers to fibers that hasrelatively thicker diameter than fibers used to form the threedimensional filtration matrix unless explicitly noted otherwise.

The use of a filter element can provide desirable properties withrespect to clot removal. In particular, filters with a three dimensionalfiltration matrix can conform to the surface of the particle to spreadthe forces over the surface of the clot. The more uniform application offorce may reduce the risk of wedging the clot in place, and may resultin a higher success rate for being able to dislodge and the removal ofthe clot. Furthermore, if portions of the clot may break free from themain section of clot, the filter element can trap the fragments andfacilitate removal of the clot while allow substantial amount of theflow to pass through. Thus, a three dimensional filtration matrix canprovide an improved element for the displacement of the clot forremoval. If a supplemental engagement structure is used, the fiber-basedfilter element provides additional support for moving the clot as wellas a collection element for capturing fragments that may break off fromclot during movement of the clot.

Embolic protection devices based on fibers can be effective atperforming some embolectomy procedures. Embolectomy procedures, ingeneral, using fiber-based embolic protection devices are describedfurther in published U.S. patent application 2008/0172066 to Galdonik etal., entitled “Embolectomy Procedures With a Device Comprising a Polymerand Devices With Polymer Matrices and Supports,” incorporated herein byreference. A fiber-based embolic protection device supplied by LumenBiomedical, Inc. called FiberNet® has been approved for use inembolectomy procedures within peripheral blood vessels. However,delivery of devices into cerebral arteries provides challenges for fiberbased devices even though the filter structure has a small lateralextent after deployment and the fibers themselves can be flexible. Thedevices described herein provide significant advances in the technologyfor the removal of clots from cerebral arteries.

The cerebral embolectomy device generally comprises a fiber-basedcomponent and a guide structure such as a very flexible wire, associatedwith the fiber based component. Upon delivery into the cerebral vessel,the fiber-based component or portions thereof can have a small radialprofile so that the device maintains sufficient flexibility for trackingalong the circuitous route into the cerebral artery. The fiber-basedcomponent or a portion thereof may or may not be secured to the flexiblewire. If the fiber-based device is not secured to a flexible wire, thefiber-based device can slide over a flexible wire for placement, forexample, until encountering a stop or the like on the flexible wire. Insome embodiments, the fiber-based device can comprise a plurality ofphysically distinct components that are engaged together to form thefilter structure. If there is a plurality of distinct fiber-basedelements, one or more of the elements can slidably engage a flexiblewire for placement in the patient. Similarly, a supplemental engagementstructure can slidably deploy over the flexible wire or the structurecan be integral with an element of the fiber-based device and theflexible wire.

The fibers in a fiber-based device component generally have at least oneend secured to an attachment element. In some embodiments, a bundle offibers are secured at an end at a common attachment element. The secondend of the fibers may or may not be secured. If the second end of thebundle of fibers is not secured, the second ends of the fibers can flareout radially from the flexible wire to participate in the formation ofthe filtration matrix formed from a non-woven fiber mat. If the secondend of the fibers in the bundle is secured, such as in a bundle toanother attachment element, the drawing of the secured second ends ofthe fibers toward the secured first ends of the fiber flares the centerof the fibers radially outward away from the guide structure tocontribute to the formation of the three dimensional filtration matrix.The manipulation of the fiber-based element to transition the fibers isdescribed further below. A plurality of fiber-based components may ormay not have a common structure with respect to attachment of the fiberends.

For delivery into a cerebral artery, it is desirable for the deviceoverall to have a relatively small diameter to facilitate the navigationof tight curves. Thus, it may be desirable for a fiber bundle tocomprise a modest number of fibers. To provide for desired diameterswhile providing a desired three-dimensional structure for the filtrationmatrix, it may be desirable to form the overall filtration matrix from aplurality of fiber bundles such that the combined bundles provide adesired total number of fibers in the overall deployed device. Theplurality of fiber bundles can be supplied with a plurality of distinctfiber-based components with each component supplying at least one bundleof fibers and/or subdividing a longer length of fibers such thatportions of a fiber deploy into a component of the filtration matrix asseparate bundles of fibers. If there is a plurality of fiber elements,the fibers within the elements may or may not be the same as the fibersin each separate element. For example, a length of fiber arranged in abundle around the flexible wire can be constrained with wrapped strip ofpolymer shrink wrap, such as a polyester, a band or the like at aposition along the length of the fiber to divide the fibers of thebundle into groups so that the separate groups deploy separately. Highstrength medically approved heat shrink tubes are commerciallyavailable. The constrained portion can slide along a guide structuresimilar to an anchor such that the portion of the constrained fibersfunctions as a secured second end for one segment of the fibers whilefunctioning as an secured first end for another segment of the fibers.Thus, in these embodiments, lengths of fiber, whether or not portions ofthe same physical fiber, compensate for reduced diameters of fiberbundles to form desired filtration matrices.

The fibers generally can have a stiffness that balances several factors.The fibers should be sufficiently flexible that the fibers fold into afiber mat that forms a filtration matrix. The flexible fibers generallydo not damage the vessel walls since they are flexible. Flexibility alsofacilitates movement of the device in a low profile configuration intothe vessel. However, the fibers can have sufficient stiffness to providefor engagement and movement of the clot. The fibers can have a circular,elliptical or other reasonable cross-sectional shape. In someembodiments, surface capillary fibers can be used. The fibers in thesame bundle may or may not be the same type of fibers. In someembodiments, it may be advantageous to combine fibers of differentmechanical and filtration properties into the same bundle to achievedesired clot retention and filtration effect.

As noted above, the fiber-based device can have a narrow profileconfiguration for placement into the cerebral artery and an extendedconfiguration that forms a filtration matrix. In general, with respectto the transition of the fiber-based device between configurations, thefiber-based device can be self-actuating and/or actuated with a pushcatheter or the like. In the self-actuating version of the device, thefibers can be formed with a shape memory. Thus, once the fibers arereleased, such as from a microcatheter, the fibers resume a naturalconfiguration extending radially from a flexible delivery wire to formthe filtration matrix. Fiber bundles that are actuated can be ofparticular interest for some embodiments since the individual fibers canbe thin and flexible while the bundle can be deployed into a desirableconfiguration with a suitable actuation device. Additionally oralternatively, struts can accompany the fibers, in which the strutsdeform upon release, such that the deformed struts tend to extend thefibers outward radially.

Struts or other support structures can also add mechanical stability tothe filtration matrix to facilitate the use of the filtration matrix tostabilize and/or push the clot. In some embodiments, the struts aredesigned to avoid contacting the vessel walls such that the struts donot injure the vessel walls. Support structures can be self-extending toform a more open support structure that supports a fiber-based matrix,although in other embodiments, the support structure is also actuated toassume a deployed configuration, such as using a common actuation toolwith the fiber-based device. Suitable memory polymers are describedfurther in U.S. Pat. No. 6,160,084 to Langer et al., entitled“Biodegradable Shape Memory Polymers,” incorporated herein by reference.Other suitable memory polymers include, for example, hydrophilic polymerfibers, including, for example, polyester fibers. These polymer fiberscan be gently heated to introduce desired curvatures, and thenmechanically straightened for placement in the vessel until released atthe point of use. Suitable spring metals that can be used for selfactuating struts include, for example, cobalt alloys, such as Elgiloy®,a cobalt-chromium-nickel alloy, MP35N, anickel-cobalt-chromium-molybdenum alloy, and Nitinol®, a nickel-titaniumalloy.

An actuation tool, such as a push catheter or the like, can be used toactuate the fibers to an extended configuration with a filtration matrixthrough advancement over the flexible wire supporting the fiber-basedelements of the clot engagement structure. If the fiber-based device isself-extending, the actuation tool can further be used to facilitatefull extension or assumption of a particularly desired configuration. Insome embodiments, an actuation tool is used to induce the transition ofthe fibers to an extended configuration forming a fiber mat as afiltration matrix. For example, the actuation tool can engage anattachment element with a plurality of attached fiber ends to move theattachment element along a delivery wire to extend radially outward thecenter of the fibers. In additional or alternative embodiments, theactuation tool, optionally with an extending engagement tool, caninterface with free ends of a fiber bundle to flare the ends of thefibers into an extended configuration. If there is a plurality offiber-based devices laterally extended along a delivery wire, a pushcatheter can be used to extend all of the fiber-based devices intoextended configurations. An actuation tool may also function as asupport structure for the fiber-based element following deployment ofthe element. In additional or alternative embodiments, the actuationtool may also actuate deployment of a support structure separately oralong with the deployment of the fiber-based element.

The filter matrix, optionally with a supplemental support or engagementstructure, can stabilize and/or move the clot in a proximal directionwithin the vessel, and the clot can be removed through a catheter. Forsofter clots, aspiration can be used to withdraw the clot into thecatheter without further intervention. For harder or more calcifiedclots, the clot can be fragmented using force between the catheter andthe filter element to break up the clot into smaller pieces that can beremoved into the catheter. In some embodiments, the clot can be wedgedbetween a small catheter and the filter element for movement in aproximal direction to deliver the clot to a larger diameter catheterthat can move easily to remove the clot from the blood vessel.

In some embodiments, the filter element can be positioned adjacent orcontacting the clot as the clot is aspirated from the blood vessel. Inadditional or alternative embodiments, the filter element can be placedcontacting the distal side of the clot as a catheter is contacted withthe proximal side of the clot to fragment the clot for removal from thevessel. In these embodiments, the catheter can have a small diameter anda high degree of flexibility such that the distal end of the cathetercan be brought optionally into a cerebral artery in the vicinity of theclot. The filter element can be used to displace the clot in a proximaldirection, i.e., upstream within the vasculature toward a catheterwithin the cerebral artery. The nature of the filter with a threedimensional filtration matrix provides for effective movement of theclot with good control of the procedure and a low risk ofre-embolization of clot fragments.

To perform the procedures in a cerebral artery, a guide catheter isgenerally initially placed in an interior carotid artery. The devicesfor the procedure in the cerebral artery can be then delivered from theguide catheter. The guide catheter can be supplied with a partially orfully occluding element, such as a balloon, that can temporarily blockor reduce flow into the cerebral arteries to facilitate removal of theclot. Catheters with partially occluding structures are described, forexample, in published U.S. patent application 2007/0060908A to Websteret al., entitled “Thrombectomy Catheter,” incorporated herein byreference.

The procedure is generally guided by appropriate visualizationtechniques. For example, the initial location of the clot can beidentified, for example, with a CAT scan, with or without contrast dye,to identify the location of treatment. During the procedure, theplacement of components of the devices generally is guided byappropriate imaging techniques, such as real time x-ray imaging. Tofacilitate this process, the devices can comprise radiopaque componentsto facilitate this process. Suitable radiopaque components include, forexample, marker bands, radiopaque fibers and other radiopaquecomponents.

In some embodiments, it can be desirable to pull the clot out from thecerebral arteries into an interior carotid artery. In the interiorcarotid artery, the clot can be aspirated with a guide catheter or otherlarger lumen catheter. A circuitous pathway connects the interiorcarotid arteries with the cerebral artery system. Due to this highlycurved transition between the vessels, there are significantly fewerstructural limitations with respect to a catheter in a carotid arterycompared with a catheter that is delivered into a cerebral artery. Inparticular, a catheter for delivery into a cerebral artery necessarilyhas a smaller lumen and is more flexible. The features that make acatheter suitable for placement into the cerebral artery make itdifficult to apply a desired degree aspiration, such as with respect tovolume and flow rate, into the catheter for the removal of the clot,which can be combined with removal of the filter element.

Therefore, it can be desirable to pull the clot into the carotid arteryfor removal into a catheter. However, this movement of the clot canprovide significant design constraints on the filter element. Inparticular, the fiber-based clot engagement element generally isdesigned to conform to the vessel walls around inner perimeter of thevessel such that the element functions essentially as a filter. If theclot engagement element along with a clot is moved a significantdistance upstream, vessel branches can be passed and generally thevessel diameter increases, and the increase can be significant if theclot is moved some distance. For example, it is possible for the vesseldiameter to increase by as much as a factor of two or more. Since thevessel diameter can change by more than a factor of two, the fibermatrix can be designed to have the ability to have significant expansionto adapt to changes in the vessel diameter. The filter element can bedesigned to maintain contact with the vessel wall as the vessel diameteraround the filter element increases due to the upstream movement of thefilter. If the filter maintains contact with the vessel wall, the filterelement can reduce or eliminate emboli from flow downstream from theclot until the clot is removed.

The filter or fiber-based clot engagement element is intended forplacement downstream from the clot. To accomplish this objective, thefilter element generally is associated with a very flexible wire thatcan navigate the circuitous vascular pathway from an interior carotidartery to the location of the clot in the cerebral artery. Since severalsharp turns in the blood vessels are located at the end of the cerebralarteries adjacent to the interior carotid arteries, sharp turns arenecessarily encountered for placement of a device into the cerebralarteries from an interior carotid artery, although additional turnscharacterize the cerebral artery system. Association of the clotengagement, i.e. filter, element with a corresponding delivery wireshould not destroy the ability of the wire to navigate the turns,although delivery of the clot engagement element onto the wire afterdelivery of the wire can indirectly address these concerns.

Generally, the clot engagement element, i.e., filter elements, comprisefibers that deploy into a fiber mat, which can form a three dimensionalfiltration matrix. The filter element is associated with a flexibledelivery wire. The filter element or portion thereof may or may not befixed to the delivery wire. In some embodiments, the filter element orportions thereof can be tracked over the delivery wire after placementof the delivery wire. If appropriate, the delivery wire can comprise astop element to engage a fiber based element portion tracked over thedelivery wire. In additional or alternative embodiments, the filterelement or a portion thereof can be attached to the delivery wire suchthat it is introduced into the patient with the delivery wire. In someembodiments, a portion of the fiber-based filter element is attached tothe delivery wire while other portions are delivered over the deliverywire. Regardless of whether or not the fiber-based filter elementcomprises a portion connected with the delivery wire, the filter elementcan optionally comprises physically distinct elements that can beassembled into the filter element for use.

In some embodiments, the clot removal procedure comprises the deliveryof a guide catheter into an interior carotid artery. Then, a guide wireor the like can be delivered into a cerebral artery with the distal endplaced past a clot within the cerebral artery. A microcatheter can bedelivered over the guidewire with its distal end past the clot, and theguidewire can then be removed. A flexible wire that supports thefiber-based clot engagement element can be delivered through themicrocatheter. If appropriate, components of the fiber-based clotengagement element and/or a support element can be delivered over theflexible wire. A deployment tool can be delivered to facilitatetransition of fibers to a deployed configuration extending outwardrelative to the flexible wire to contact vessel walls, and the deliveryof the deployment tool can be performed after removing themicrocatheter. Once the fiber-based element is fully assembled anddeployed along with any support structures, the clot can be engaged forremoval. The clot can be brought to an aspiration catheter, which can bepositioned within a cerebral artery or an internal carotid artery. Insome embodiments, the guide catheter within the interior carotid arterycan be used as an aspiration catheter. With the clot engagementstructure or element deployed, an auxiliary treatment structure, such asan atherectomy device, a stent, an angioplasty balloon or the like canbe deployed prior to translation of the clot engagement structure orelement in a proximal direction.

Other devices have been designed with the objective of removing clotsfrom vessels. In general, these devices are designed to grip the clot orfragments thereof to effectuate its removal. For example, spiral shapeddevices for gripping clots are described in U.S. Pat. No. 7,534,252 toSepetka et al., entitled “Systems, Methods and Devices for RemovingObstructions from a Blood Vessel,” incorporated herein by reference. Adevice designed for gripping clots from a proximal approach is describedfurther in published PCT application WO 2006/031410A to Bose et al.,entitled “System and Method for Treating Ischemic Stroke,” incorporatedherein by reference. In contrast with these devices the present devicesare intended to stabilize and pull the clot without necessarily grippingthe clot. Also, the fiber-based devices described herein can effectivelyprovide a filtration function to reduce or eliminate re-embolization.

Fiber bristle devices for removing clots are described in published U.S.patent application 2009/0306702 to Miloslavski et al., entitled “Devicefor the Removal of Thrombus,” incorporated herein by reference. Thesedevices have a brush style design intended to capture and/or fragmentthe clot while gripping fragments. In contrast, the present devices areintended to form a filtration matrix with a relatively small lateralextent that provides for pushing the clot for removal with a catheter.The filtration matrix may additionally capture and retain any debris orbreak off from the clot during the removal process. The fibers of thedevices herein are incorporated into a significantly different structureto provide correspondingly different functionality. In particular, thefibers of the element generally are very thin such that a mat of fiberscan be formed with appropriate filtering ability without damaging thevessel walls and in some embodiments having the ability to conform tochanging diameters of the vessel walls as the element is moved withinthe vasculature. The combination of a fiber-based element that forms afiber mat with a support element can be particularly effective based onthe combined features of the components.

Structural Elements of the Embolectomy Devices and Methods of Making

The embolectomy devices generally comprise a flexible wire and afiber-based clot engagement structure or element that engages theflexible wire. The fiber-based elements generally comprise a bundle offibers, generally in a non-self extending structure, in which the fibersmay be fixed at one or both ends to an anchor or the like. The devicescan further comprise a support structure and/or an actuation tool thatalso engage the flexible wire. A support structure may or may not alsofunction as an actuation tool. The components that engage the flexiblewire may slide over the flexible wire or are connected fixedly to theflexible wire. One or more catheters can be used to facilitate theprocedure, such as a guide catheter, a microcatheter and/or anaspiration catheter, although the guide catheter can also be configuredas an aspiration catheter. The proximal end of the device, introducers,hemostatic valves and the like, such as those elements known in the art,can be placed to provide for introduction of elements into the patient'sblood vessel, and various fittings, such as Luer lock fittings and thelike, can be used for the delivery of the various components outside thepatient by guiding the components into the patient's blood vessels.

Referring to FIG. 1, two embodiments of the fiber bundle in differentconfigurations are illustrated. FIG. 1( a) is a side perspective view ofa fiber cartridge 100 with a bundle of fibers 102 having one end fixedwith a fiber attachment element 104 while the other end of the fibersremain un-constrained. The fibers in the bundle generally align along aguide wire 108 in a narrow profile configuration. FIG. 1( b) shows afiber cartridge 200 with a bundle of fibers 202 having both ends fixedwith fiber attachment element 204 and 206, respectively. The middleportion of the fibers is not secured or constrained. The fibers in thebundle 200 generally align a guide wire 208 in a narrow profileconfiguration. Both fiber bundles 100, 200 can be designed for fixedattachment to the wire 108 or 208 through fiber attachment elements 104or 204, respectively. In some embodiments, the fiber attachment elementshave a slide that can translate over the delivery wire or an anchor thatis secured at a fixed position of the delivery wire. The wire 108 and208 can be the delivery wire or can have a lumen to slide over aseparate delivery wire. The un-constrained portion of the fibers canflare radially outward to an extended deployed configuration. Referringto FIG. 1( c), a side perspective view of the fiber cartridge 100 ofFIG. 1( a) is shown in an extended deployed configuration. Referring toFIG. 1( d), a side perspective view of the fiber cartridge 200 of FIG.1( d) is shown in an extended deployed configuration. The unconstrainedend or portion of the fibers flares outward to form a three dimensionalfiltration matrix that is capable of retain clot while trappingbreak-offs from the clot.

The fibers of the fiber bundle can be approximately uniformly fixedaround a central axis approximately at the center of the attachmentelement. Also, the attachment element generally has a central lumenroughly aligned with the central axis for sliding over the flexibledelivery wire or is attached fixedly to the flexible delivery wireroughly at the position of the central axis. The approximate cylindricalsymmetry of the bundle around the delivery wire facilitates thedeployment of the fiber bundle into a filter matrix that has a desirableconfiguration across the blood vessel upon deployment. The fibers can beselected to have desired mechanical properties in the vessel. Ingeneral, the fibers should be flexible so that the fibers can bedelivered into the vessel and such that the fibers do not injure thevessel wall. Generally, the fibers are formed from polymers, such asorganic polymers. Suitable polymers include, for example, polyamides(e.g., nylon), polyesters (e.g., polyethylene teraphthalate),polyacetals/polyketals, polyimide, polystyrenes, polyacrylates, vinylpolymers (e.g., polyethylene, polytetrafluoroethylene, polypropylene andpolyvinyl chloride), polycarbonates, polyurethanes, poly dimethylsiloxanes, cellulose acetates, polymethyl methacrylates, polyether etherketones, ethylene vinyl acetates, polysulfones, nitrocelluloses, similarcopolymers and mixtures thereof. Based on desirable properties andexperience in the medical device field, suitable synthetic polymersinclude, in particular, polyether ether ketones, polyacetals, polyamides(e.g., nylons), polyurethanes, polytetrafluoroethylene, polyesterteraphthalate, polycarbonates, polysulfone and copolymers and mixturesthereof. Fibers can be formed from a radiopaque material, as describedin published U.S. patent application 2007/0172526A to Galdonik et al.,entitled “Radiopaque Fibers and Filtration Matrices,” incorporatedherein by reference.

The fibers can have a suitable cross sectional shape to provide desiredmechanical properties. In some embodiments, the fibers can have acircular cross section, oval cross section or other convenient shape. Insome embodiments, surface capillary fibers can be used, which have oneor more surface capillaries extending along the length of the fiber. Theuse of surface capillary fibers for three dimensional filtrationmatrices for embolic protection devices is described further inpublished U.S patent application 2005/0209631A to Galdonik et al.,entitled “Steerable Device Having a Corewire Within a Tube andCombination With a Functional Medical Component,” incorporated herein byreference.

A particular device can comprise one or more types of fibers. In someembodiment, the same bundle of fibers can comprise one or more types offibers to provide desired mechanical and filtration properties. Thethickness of the fibers can be selected appropriately for the particularuse of the fiber. Fiber thickness can be measures in several ways. Theradius of the fiber can be roughly estimated from the assumption of acircular cross section. Alternatively, one can define an averagediameter by taking an average cross section and then averaging thelength of segments through the center of the cross section thatintersect the circumference of the cross section. Also, calipers can beused to measure thickness, which can be averaged to obtain a value ofthe diameter. These various approaches at estimating the radius ordiameter generally give values of roughly the same magnitude.

Also, in the fiber field, a pragmatic way has been developed tocharacterize fiber thickness without the need to resort to magnificationof the fibers. Thus, fiber thickness can be measured in units of denier.Deniers correspond to the number of grains per 9,000 meters of yarn witha larger value corresponding to a thicker fiber. In some embodiments,suitable fibers have diameters from 1 micron to about 75 microns, infurther embodiments from about 2.5 microns to about 50 microns, and inadditional embodiments from about 5 microns to about 40 microns. Asmeasured in denier, suitable fibers can have sizes ranging from about0.02 denier to about 50 denier in size, in additional embodiments fromabout 0.05 denier to about 30 denier, in some embodiments from about 0.1denier to about 20 denier, in other embodiments from about 0.2 denier toabout 15 denier and in further embodiments from about 0.4 denier toabout 10 denier. As noted above, supplemental engagement or supportstructures can be formed from thicker filaments, which are generallyincluded in smaller numbers to provide added support to the fiber-basedclot engagement structures. For filaments included in a supplementalsupport structure, the filaments generally have a diameter from about 15microns to about 300 microns (0.3 mm, 0.012 inches), in furtherembodiments from about 20 microns to about 275 microns and in otherembodiments from about 250 microns. The number of fibers can be selectedbased on the diameters with the constraint of the inner diameter of adelivery catheter, such as a microcatheter. For a supplemental supportstructure, the structure can comprise from about 4 to about 25 polymerfilaments. For the fiber based filter structure, a bundle of fibersgenerally comprises from about 25 to about 500 fibers, in furtherembodiments from about 30 to about 400 fibers and in additionalembodiments from about 35 to about 300 fibers. A range of biocompatiblepolymers have been approved for use in a devices placed into patients,such as polyesters. A person of ordinary skill in the art will recognizethat additional ranges of fiber thickness in diameter measurements or indenier and fiber numbers are contemplated and are within the presentdisclosure.

The lengths of the fibers should be selected such that the deployedfibers fill the vessel lumen. Thus, if the fibers are bent in thedeployed configuration, the fibers should have lengths greater than afactor of 2 larger than the vessel radius. The devices can be suppliedwith different sizes available for selected deployment based on the sizeof a particular target vessel. If the devices are designed for movementof a clot to the carotid artery, the size of the carotid artery can beused to select the device size without reference to the size of thevessel where the clot is initially located. In some embodiments relatingto the use of a plurality of fibers to expand within the lumen of apatient's vessel, it is generally appropriate to use fibers that have alength from about 2.2 to about 15 times the vessel radius, in someembodiments from about 2.4 to about 12 times the vessel radius and infurther embodiments from about 2.6 to about 8 times the vessel radius.In particular, if the fiber-based filter element is used to drag theclot into the carotid artery, the vessel diameter around the filterelement can change, for example, from roughly 1.5 to 2 mm in diameter toabout 5.5 to 6 mm in diameter. For placement in a human vessel, thefibers generally have a length from about 0.5 mm to about 100 mm, inother embodiments from about 1 mm to about 25 mm, and in furtherembodiments from about 2 mm to about 15 mm. A person of ordinary skillin the art will recognize that additional ranges of fiber numbers andfiber length within the explicit ranges are contemplated and are withinthe present disclosure.

For spring metal elements, either struts or elements for a supplementalengagement structure, the spring metal elements generally have acircumference from about 0.001 inches (24 microns) to about 0.05 inches(1200 microns), in further embodiments from about 0.002 inches (48microns) to about 0.03 inches (7200 microns) and in other embodimentsfrom about 0.003 inches (72 microns) to about 0.02 inches (480 microns).In general, the supplemental engagement structure comprises from about 2to about 10 wires or other shaped elements of spring metal. A person ofordinary skill in the art will recognize that additional ranges ofdiameters and number of wires within the explicit ranges above arecontemplated and are within the present disclosure. The metal elementsgenerally can have any reasonable cross sectional shape consistent withthe element design, such as round or ribbon shaped. The appropriatelength of the metal element depends on the specific design and should beconsistent with the deployed shape within the vessel.

In general, catheters can be formed from metal, polymers andcombinations thereof. For example, some catheters can be formed frompolymer tubes with embedded metal reinforcement. Flexible wires andother metal elements can be formed from stainless steel, titanium,spring metals, combinations thereof or the like.

Referring to FIG. 2, embodiments of microcatheter with filter elementsare illustrated. FIG. 2( a) is a fragmentary side perspective view of afilter element comprising a fiber bundle 110 with a single bound end 114fixed to a delivery wire 112 protruding distally outside a microcatheter116. FIG. 2( b) is a fragmentary side view of an embodiment with adelivery wire 118 that has a stop 120 and a filter element 122 thatslides over the delivery wire until it hits the stop. The rigid stop 120at or near the distal end portion of the device generally has a diameterlarger than the body of the delivery wire 118. The delivery wire 118 mayadditionally have an optional coil tip 124 to facilitate the maneuver ofthe delivery wire inside a blood vessel. In some embodiments, the filterelement 122 comprises a bundle of fibers 126 that can be attached to afiber attachment element 128 with an adhesive, a band or the like and/ormelted polymer from heat bonding the fibers of the bundle.

The ends of the fibers can be secured in a roughly parallel orientationrelative to the flexible delivery wire and approximately uniformlydistributed around the circumference of the delivery wire. Theorientation of the fixed ends of the wire is consistent with a lowprofile delivery configuration of the fibers aligned approximately alongthe axis of the delivery wire. If desired, a radiopaque band 129 can besecured at the fiber attachment element 128. FIG. 2( c) shows anotherembodiment of a filter element 130 advanced out of distal end of amicrocatheter 132. The filter element comprises a combination of filtercartridge bundles 134, 136, 138, 140, and 142 distributed along thedistal portion of the delivery wire 144. The number, the orientation,and the composition of the fiber cartridge bundle can be varied to suitea variety of needs. In the embodiment shown in FIG. 2( c) for example,fiber bundles 134 and 136 assumes an opposite orientation compared tothe fiber bundles 140 and 142, while fiber bundle 138 has both ends ofthe fibers constrained. The fibers bundles shown in FIG. 2( c) oncedeployed may provide complementary mechanical and filtration propertiesto result in improved performance in clot removal process. In general,the device can comprise one fiber bundle, two fiber bundles, three fiberbundles, four fiber bundles, five fiber bundles, six fiber bundles ormore than six fiber bundles. In some embodiments, at least some of thefibers bundles are non-woven. The fiber bundles can be made out of sameor different materials, having the same or different constructions, aswell as the same or different sizes in terms of number of fibers used,the length and thickness of the fibers used. The fiber bundles canassume any of the structure described herein.

Referring to FIG. 3, embodiments of interaction between filter elementand push and/or micro catheter are shown. FIG. 3( a) shows the filterelement 122 of FIG. 2( b) fully deployed by its interaction with amicrocatheter 146. Specifically, the filter element 122 comprises aplurality of fibers 126 having one end of the fibers fixed on a fiberattachment element 128 that is delivered on a guidewire 118. After thefilter element 122 is advanced out of the microcatheter 146, thenon-bound or non-fixed end of the fibers flares slightly such that whenthe fiber element is pulled against the microcatheter, the fibers 126becomes fully extended to a fully deployed configuration. If desired, aradiopaque band 148 can be secured at the distal portion of themicrocatheter 146 to facilitate the delivery and deployment of thefilter element and the microcatheter.

An optional push catheter may also be used. FIG. 3( b) shows anembodiment of the push catheter 152 having an extendable element orsection 154 used to deploy a filter element 155. The filter element isdelivered on a guidewire 157, which has an optional tip section 159 thatprovide additional navigation during the delivery. The expandableelement 154 can be formed, for example, from a slotted tube 156 orseparate micro-filaments fused to the catheter, although otherextendable structures can be similarly used. The expandable element orsection 154 can have a low profile configuration until push catheter 152engages fiber-based element 155 such that the force against thefiber-based element extends the extendable element 154. A push cathetercan optionally be used as a supplemental engagement structure such thatthe push catheter and fiber-based filter element are used together toremove the clot. The push catheter can serve a dual purpose of extendingthe fibers and facilitating the movement of the clot.

Referring to FIG. 4, an embodiment of a fiber-based filter element 158with a heat shrink sheet 160 combined with fibers 162 is illustrated ina low profile configuration and in an extended configuration. FIG. 4( a)shows a thin wall of heat shrink polymer jacket 160 on the exterior of afiber bundle 162, in which the polymer jacket 160 has slits 164 suchthat the polymer jacket can assume the extended configuration. While aheat shrink polymer jacket can be convenient, other polymer jacketmaterials can be used and appropriately assembled, as desired. Thefibers are fixed on one end to a first attachment element 163 and on thesecond end to a second attachment element 165. First attachment element163 and second attachment element 165 are respectively associated withtubes 167 and 169 that have an inner diameter suitable for sliding overa flexible wire associated with delivery of the device past the clot.FIG. 4( b) shows the outer heat shrink jacket covers the fiber bundle ina deployed or extended configuration. This fiber-based element isdeployed in a similar way as other fiber-based elements. The jacketedfiber-based elements of FIG. 4 can be used alone or in combination withother fiber-based element which may or may not have polymer jackets.

Referring to FIG. 5, various views and configurations are shown of anembodiment of a filter element 166 comprising multiple fiber cartridges168, 170, 172 with fiber tail formed from longer fibers and PET heatshrink jacket or structure support. Small sections of heat shrink wrap,which can be optionally replaced or supplemented with bands 171 and 173,such as radiopaque bands, metal bands, polymer bands or the like,effectively constrain and therefore divide long fibers into sectionsthat separately deploy as fiber mats as a filtration matrix such thatthree distinct fiber mats 168, 170, and 172 are combined within thefiltration matrix. The band 173 functions as a secured second end forfiber cartridge 168 while functioning as a secured first end for fibercartridge 170. The band 171 functions as a secured second end for fibercartridge 170 while functioning as a secured first end for fibercartridge 172. The second end of the fiber cartridge 172 remainsunconstrained. In some embodiments, the bands 171 and 173 can slidealong the guide wire 175 similar to an anchor. An optional distal coil187 can be integrated to the distal end of the guide wire 175 tofacilitate the delivery of the device into a desired location inside avessel. The overall lengths of fiber could compensate for reduceddiameters of fiber bundles to form desired filtration matrices.

FIG. 5( a) is a side view of the filter element in a delivery or narrowprofile configuration. FIG. 5( b) is a side view of the filter elementof FIG. 5( a) in a deployed or extended configuration. In someembodiments, the bundle of the fibers is non-woven. Thus, in theembodiment of FIG. 5, multiple fiber-based elements are effectivelyformed from long fibers that are subdivided to form the individualfiber-based elements. The fiber-based element of FIG. 5 can be used incombination with additional fiber-based elements that are slide over theflexible wire. While FIG. 5 is directed to long fibers divided intothree elements, long fibers can be similarly divided as desired into twoelements, four elements, five elements or more than five elements.

Referring to FIG. 6, various configurations are shown of a filterelement 176 comprising multiple free ended fiber cartridges 178, 180,182 with a fiber tail that slide along a delivery wire 184. FIG. 6( a)is a side view of the filter element 176 in a delivery or narrow profileconfiguration. Fiber cartridge 178 is secured at one end with a fiberattachment element 177, fiber cartridge 180 is secured at one end with afiber attachment element 179, and fiber cartridge 182 is secured at oneend with a fiber attachment element 181. The free end of the fibercartridge 178 can be temporarily constrained by the fiber attachmentelement 179, the free end of the fiber cartridge 180 can be temporarilyconstrained by the fiber attachment element 181, and the free end of thefiber cartridge 182 can remain unconstrained. FIG. 6( b) is a side viewof the filter element 176 in a partially deployed or extendedconfiguration where cartridge 182 slides along delivery wire 184 in anextended configuration. The free end of the fiber cartridge 180 is freedfrom the constraints of fiber attachment element 181 and is in apartially deployed configuration. The free end of the fiber cartridge178 is constrained by fiber attachment element 179 and therefore isstill in an un-deployed configuration. Referring to FIG. 7, deploymenttools and application of a deployment tool is shown. FIG. 7( a) is aphotograph of a push catheter 190 with a polymer filament cartridge 192as the deployment tool 188 in an expanded configuration. The deploymenttool can engage fibers of a filter element to extend the fibers to anextended configuration. FIG. 7( b) is a photograph of the push catheter190 with the expandable element 192 in a reduced diameter deliveryconfiguration in combination with a filter element 194. Push catheter190 can be tubular, such as a metal, polymer or composite tube, an openwoven structure as shown in the alternative embodiment in the insert ofFIG. 7( c) since the push catheter does not hold fluid, or otherappropriate structure that allows for pushing the deployment tool intoposition. The filter element comprises three filter cartridges 191, 193,and 195 that can be separate such as the embodiment shown in FIG. 6 orconnected such as the embodiment shown in FIG. 5. FIG. 7( c) is adiagram of the device of FIG. 7( b) showing the filter element 194inside a vessel 196 while the filament cartridge 192 in a reduceddiameter delivery configuration inside a microcatheter 198 with thefilter element 194 advanced distal to the filament cartridge 192. FIG.7( d) is a diagram showing the filament cartridge 192 advanced outsidethe microcatheter 198 by the push catheter 190 and deployed into theextended configuration. FIG. 7( e) is a diagram showing the filamentcartridge 192 advanced further to push the filter cartridges 191, 193,and 195 into a fully deployed configuration. The fully deployed filtercartridges have extended configurations that push against the wall ofthe vessel 196.

In some embodiments, the filament cartridge is self-extendable. FIGS. 7(a 1)-(a 3) are additional embodiments of the deployment tools.Specifically, FIG. 7( a 1) is a schematic diagram of a push catheter190′ with triangular shaped filament cartridge 192′ as the deploymenttool in an expanded configuration. FIG. 7( a 2) is a schematic diagramof a push catheter 190″ with star shaped filament cartridge 192″ as thedeployment tool in an expanded configuration. FIG. 7( a 3) is aschematic diagram of a push catheter 190″′ with star shaped filamentcartridge 192″′ as the deployment tool in an expanded configuration. Thestar shaped filament cartridge 192″′ can have padding to make thefilaments thicker. The deployment tools can be formed from shape memorymetals or suitable thicker polymer fibers.

Referring to FIG. 8, a side view of a device is shown. The devicecomprises a filter element 210 with a polymeric filaments supplementalengagement structure 212, comprising a plurality of polymeric filamentswith both ends of the filaments secured by filament support structures211 and 213. The filament support structures 211 and 213 can be fixed orslidable on the delivery wire 150. The filter element 210 comprises abundle of fibers with both ends of the fibers secured by fiberattachment elements 214 and 215. The fiber attachment elements 214 and215 can be fixed or slidable on the delivery wire 150. The filterelement 210 and the polymeric filament supplemental engagement structure212 may or may not be integrally constructed to be connected to eachother. The supplemental engagement structure 212 is combined with thefilter element 210 to provide support for the filter element so thecombination can retain clot while effectively trap emboli by conformingto the inner perimeter of the vessel during the entire clot removalprocess. The filter element can then engage the clot as well as toprovide the ability to capture any fragments of the clot that separatesfrom the clot. In general, the filaments of the supplemental engagementstructure are significantly thicker than the fibers of the filterelement. The filaments may be self-extendable while the bundle of fibersis deployed into an extended configuration with appropriate actuation.The device may be contained in a microcatheter in a reduced diameterdelivery configuration for placement within a vessel. Once themicrocatheter is released, the filaments expand into an extendeddeployment configuration as shown. The filter element maybeindependently deployed using a pushing element.

Referring to FIG. 9, a device comprising the filter element 210 and aNitinol frame supplemental engagement structure is shown. The Nitinolframe supplemental engagement structure and the filter element can beintegrally constructed within to resulting element or can be separateelements that are deployed adjacent each other. The device may becontained in a microcatheter in a reduced diameter deliveryconfiguration in which the Nitinol elements are straightened fordelivery. Once the microcatheter is released, the Nitinol frame expandsinto an extended deployment configuration as shown based on the shapememory of the metal. The filter element 210 shown in FIG. 9( a) is in areduced diameter delivery configuration. The filter element 210 may beindependently deployed into an extended configuration using a pushingelement 218 and a view of the Nitinol frame supplemental engagementstructure 216 with the filter element 210 deployed into an extendeddeployment configuration is shown in FIG. 9( b). The Nitinol framesupplemental engagement structure 216 comprises a plurality of Nitinolwires with one end of the wires secured at an attachment element 217.The attachment element 217 can be fixed or slidable on the delivery wire220. The filter element 210 comprises a bundle of fibers with both endsof the fibers secured by fiber attachment elements 214 and 215. Analternative embodiment of the Nitinol frame is shown in FIG. 9( c) whereNitinol frame 220 comprises a plurality of Nitinol wires with one end ofthe wires secured at an attachment element 219. The Nitinol wires arecoiled upon release in the vessel to reduce abrasion against asurrounding vessel.

A representative configuration of the proximal end of the system that ismanipulated outside of the patient is shown in FIG. 10. In general, theparticular components vary based on the particular design selected andthe order of use of the components. Referring to FIG. 10, the proximalend of a clot removal system 300 is shown. Guide catheter 302 provides acentral lumen for the placement of other components of the system. Afirst touhy-borst fitting 304 is secured to the proximal end of guidecatheter 302. First touhy-borst fitting 304 has a side arm 306 for theattachment of a fluid exchange element 308. Fluid exchange element 308can be a syringe, pump or other appropriate fluid flow control device,which can be used to deliver a fluid, such as contrast dye or amedication, or to applied suction to remove liquid. In alternativeembodiments, other suitable fittings can be used, and the fitting cancomprise additional arms, such as embodiments with a first area forfluid delivery and a second arm for fluid withdrawal.

In the embodiment of FIG. 10, an optional aspiration catheter 320 isdelivered through a valve of first fitting 304. As noted herein,aspiration can be performed with the guide catheter. The embodiment ofFIG. 10 allows for aspiration through either or both of aspirationcatheter 320 and guide catheter 302. Aspiration catheter 320 is shownwith an over-the-wire configuration. Suitable rapid exchange aspirationcatheters are described in published U.S. patent application2007/0060944A to Boldenow et al., entitled “Tracking AspirationCatheter,” incorporated herein by reference.

Second touhy-borst fitting 322 is attached at the proximal end ofaspiration catheter 320. Second touhy-borst fitting 322 has a side arm324 for attachment to fluid aspiration device 326, which can be asyringe, pump or the like. Microcatheter 328 extends through a valve ofsecond fitting 322. In some embodiments, any microcatheters used in theprocedure are removed prior to the placement of a separate aspirationcatheter, but in the embodiment of FIG. 10, both catheters aresimultaneously loaded through guide catheter 302. Third fitting 330 islocated at the proximal end of microcatheter 328. Flexible wire 332extends from third fitting 330. Fiber-based clot engagement elements aregenerally supported on flexible wire 332. Suitable actuation tools orseparate support structures for use with the fiber-based elements can besimilarly delivered through the appropriate fitting.

Method of Using Embolectomy Devices

The procedure for clot removal generally comprises the delivery of thefiber-based clot engagement element in the vessel past the clot, pullingthe clot in a proximal direction and aspirating the clot from thevessel. The process can further comprise breaking up the clot tofacilitate clot removal. The clot engagement devices can generallycomprise any of the structures described in the previous section. Theprocedure is designed to reduce or eliminate any release of fragments ofthe clot as emboli during the removal of the clot. Following removal ofthe clot, the fiber-based device is recovered, possibly with continuedaspiration to limit or prevent release of fragments.

With respect to initial placement of the fiber-based structure, theelement is presented past the clot. In some embodiments, the flexiblewire can be directly delivered through the clot from a guide catheterwithin a carotid artery. In other embodiments, a microcatheter is firstplaced with its distal end past the clot, and the microcatheter can bedelivered optionally over a guidewire, which can be placed with itsdistal tip past the clot. If a microcatheter is in place, thefiber-based element can be delivered through the microcatheter. Once afiber-based element is in place past the clot, any additionalfiber-based elements can be delivered to the desired location. Anappropriate actuation element can then be used to deploy the fiber-basedelement.

Depending on the size of the clot and the corresponding aspirationcatheter, it may or may not be convenient to aspirate the whole clot. Insome embodiments, the clot can be drawn to the tip of the aspirationcatheter and force against the aspiration catheter can be used to breakup the clot for removal through the aspiration catheter. The use of thefiber-based element is particularly advantageous in this context sinceany emboli that break off from a fragmenting clot can be trapped by thefiber-based element for subsequent aspiration or removal through a guidecatheter.

Referring to FIG. 11, a process of clot removal using an embodiment ofthe treatment device is illustrated. FIG. 11( a) shows a filter element230 at the distal portion of a delivery wire 232 is advanced cross aclot 234 in the cerebral artery 236. The placement of the filter elementcan be facilitated by monitoring the relative positions of the clot anda radio opaque band on the filter element. The delivery wire 232 isadvance from a microcatheter 238, which resides inside the lumen of aguide catheter 240. The guide catheter is advanced in the carotid artery242 close to the sharp bend in the cerebral artery. In some embodiments,the delivery wire with the filter element may be advanced pass the clotdirectly. Alternatively or additionally, a guide wire may optionally beused to facilitate the delivery of the filter element. Specifically, theguide wire can be first delivered across the clot. The microcatheter canthen be advanced pass the clot over the guide wire. Once themicrocatheter passes the clot, the guidewire is retrieved, and thedelivery wire with the filter element is advanced pass the clot insidethe microcatheter. The microcatheter can then be retrieved back to beclose to the guide catheter.

FIG. 11( b) shows the filter element being deployed into a fiber matdistal to the clot. An optional actuation tool may be used to facilitatethe deployment of the filter element. FIG. 11( c) shows the fiber matretains the clot when the delivery wire is retrieved back towards themicrocatheter. FIG. 11( d) shows when the clot is pulled close to theguide catheter, an optional occlusive balloon 246 can be deployed totemporarily block the blood flow or a portion thereof inside the vesselwhile suction 244 is being applied, and the delivery wire is beingpulled back towards the microcatheter with the fiber mat. The clot 234,subjecting to both the pulling and/or the suction forces can be thussuccessfully removed. Any fragments that break off the clot can becontrolled with the filter matrix and removed with suction or with thefilter matrix. In some embodiments, when the clot is particularly hard,the clot engagement device can be pulled against the aspiration catheterto break up the clot to be removed by the aspiration.

Referring to FIG. 12, a process of a clot removal using an embodiment ofthe treatment device with an angioplasty balloon 256 is illustrated.FIG. 12( a) shows a filter element 250 in an extended deployedconfiguration distal to clot 252 in a vessel 254 with the balloon 256being placed at the location of the clot. An optional actuation tool maybe used to facilitate the deployment of the filter element. FIG. 12( b)shows the balloon 256 being deployed to dislodge the clot to formfragments 258. FIG. 12( c) shows the deployed fiber element 250 retainsthe dislodged clot fragments 258 while the deflated balloon 256 is beingretrieved along the guidewire 266. FIG. 12( d) shows when the dislodgedclot fragments 258 are pushed close to a guide catheter 260, an optionalocclusive balloon 262 can be deployed to temporarily block the flow or aportion thereof inside the vessel while suction 264 is being applied,and the delivery wire 266 is being pulled back towards a microcatheter268 with the deployed fiber element. The dislodged clot fragments 258,subjecting to both the pulling and/or the suction forces can be thussuccessfully removed.

Packaging and Distribution

The flexible wire and fiber-based elements of the clot engagement toolare generally packaged together in a sterile package. Suitablesterilization procedures are known in the art and other may bedeveloped. Additional components of the overall system may or may not bepackaged together. For example, depending on the design of the guidecatheter, a conventional may be used, which could be packagedseparately. Similar issues relate to other components of the overallsystem. In general, proprietary components used in the system may bepackaged together for convenience.

The embodiments above are intended to be illustrative and not limiting.Additional embodiments are within the claims. In addition, although thepresent invention has been described with reference to particularembodiments, those skilled in the art will recognize that changes can bemade in form and detail without departing from the spirit and scope ofthe invention. Any incorporation by reference of documents above islimited such that no subject matter is incorporated that is contrary tothe explicit disclosure herein.

1. An acute stroke treatment device comprising one or more flexibledelivery wires and a fiber-based clot engagement element that comprisesat least one bundle of unwoven fibers and a first attachment elementwherein each fiber of the bundle is secured at one end to the firstattachment element, wherein the first attachment element eithercomprises a slide that can translate over the delivery wire or an anchorthat is secured at a fixed position around the circumference of thedelivery wire, wherein if the first attachment element has an anchorfixed to the delivery wire, the other end of the fibers are unsecured orare secured in a bundle at a second attachment element without fixedattachment to an actuation structure, and wherein the bundle of fibershave a first low profile delivery configuration and a secondconfiguration with a portion of the fibers that is unsecured flaringoutward relative to the delivery wire to have dimensions suitable toconform to the changing inner perimeter of a blood vessel and the fibersdo not spontaneously transition between the first configuration and thesecond configuration.
 2. The device of claim 1 wherein the unwovenfibers in the first configuration are substantially parallel to eachother along the delivery wire in the bundle.
 3. The device of claim 1wherein the fibers in the second configuration form a three dimensionalfiltration matrix comprising effective pores with a distribution ofsizes within the matrix while the fibers remain unwoven.
 4. The deviceof claim 1 further comprising a radio-opaque band on the firstattachment element.
 5. The device of claim 1 wherein the fiber basedelement comprises a plurality of unwoven fiber bundles.
 6. The device ofclaim 5 wherein a long non-woven fiber bundle is anchored at one or morepositions along the fiber around the circumference of the flexible wireto form the plurality of fiber bundles that are inter-connected to eachother.
 7. The device of claim 5 wherein the plurality of fiber bundleseach have its own attachment element.
 8. The device of claim 5 whereinfiber bundles have one or both ends of the fibers secured.
 9. The deviceof claim 1 further comprising heat shrink wrap around a portion of thefiber bundle such that the wrap forms a jacket around a portion of thefiber-based structure in the second configuration.
 10. The device ofclaim 1 further comprising a supplemental engagement structure mountedor delivered on the flexible wire.
 11. The device of claim 10 whereinthe supplemental engagement structure is a filament structure comprisinga plurality of polymeric filaments, wherein the polymeric filaments aresubstantially thicker than the fibers in the fiber bundle.
 12. Thedevice of claim 10 wherein the supplemental engagement structure is aNitinol frame comprising a plurality of self-extendable Nitinol wires.13. The device of claim 1 further comprising a mechanical treatmentdevice delivered on the flexible wire.
 14. The device of claim 13wherein the mechanical treatment device is an atherectomy device, astent, or an angioplasty balloon.
 15. The device of claim 1 wherein anactuation tool or deployment tool is used to transition the fiber-basedelement from the first configuration to the second configuration. 16.The device of claim 15 wherein the actuation tool is a microcatheter.17. The device of claim 15 wherein the deployment tool comprises afilament cartridge comprising a plurality of filaments.
 18. A system forthe treatment of an acute stroke comprising: the fiber based clotengagement element of claim 1; an actuation tool having a tubular distalend with an inner diameter such that the distal tip of the actuationtool slides over the delivery wire to deploy the fibers of thefiber-based clot engagement element to the second flared configuration;and an aspiration catheter comprising a lumen with a distal opening inwhich the aspiration catheter can be delivered over the flexibledelivery wire.
 19. A method for the delivery of a clot engagement devicewithin a cerebral artery, the method comprising: positioning a distalopening of a guide catheter inside an interior carotid artery;delivering the clot engagement device through the guide catheter toaccess a cerebral artery downstream from the interior carotid artery,wherein the clot engagement device comprises a fiber-based clotengagement element supported by a flexible wire; and advancing anactuation element over the flexible wire to deploy the fiber-basedelement to an extended configuration with the fibers conforming to theinner perimeter of the arteries, wherein the movement of the actuationelement is unconstrained over the flexible wire.
 20. The method of claim19 wherein the flexible wire is advanced directly to access the cerebralartery.
 21. The method of claim 19 wherein the delivery step comprisesthe steps of: delivering a guidewire to access the cerebral artery,delivering a microcatheter over the guidewire to access the cerebralartery, retrieving the guidewire; delivering the clot engagement deviceon the flexible wire through the microcatheter to access the cerebralartery.
 22. The method of claim 21 further comprising pulling the distalopening of the microcatheter behind the clot engagement device to exposethe clot engagement device inside the artery, and then pushing themicrocatheter forward against the clot engagement device to actuate thedevice.
 23. The method of claim 19 wherein the actuation element is apush catheter coupled with a deployment tool comprising a filamentcartridge and the filament cartridge is deployed into an extendedconfiguration before helping to deploy the clot engagement device. 24.The method of claim 23 wherein the filament cartridge comprises aplurality of filaments that can be a filament bundle, triangular shapedfilaments, or star shaped filaments.
 25. The method of claim 23 furthercomprising using the push catheter to push the deployed deployment toolto deploy the clot engagement device.
 26. A method for the removal of ablood clot from a cerebral artery causing an acute stroke event, themethod comprising: positioning a fiber-based clot engagement deviceinside the cerebral artery distal to the blood clot on a delivery wire;deploying the fiber-based clot engagement device to an extendedconfiguration with at least a portion of the fibers extending outwardrelative to the delivery wire to conform to the inner perimeter of thecerebral artery; pulling the deployed clot engagement device towards anaspiration catheter positioned inside an interior carotid artery so theclot engagement device becomes engaged with the clot, wherein the fibersof the clot engagement device remain conforming to the changing innerperimeter of the arteries and thereby remain engaging the clot duringthe pulling process, and applying aspiration through the aspirationcatheter while drawing the clot into the aspiration catheter withproximal movement of the clot engagement device.
 27. The method of claim26 further comprising dislodging the clot with a mechanical treatmentdevice.
 28. The method of claim 26 wherein the mechanical treatmentdevice is an atherectomy device, a stent, or an angioplasty balloon. 29.The method of claim 26 wherein the clot engagement device furthercomprises a supplemental engagement structure.
 30. The method of claim29 wherein the supplemental engagement structure is a filament structurecomprising a plurality of polymeric filaments, a Nitinol framecomprising a plurality of self-extendable Nitinol wires, or acombination thereof.
 31. The method of claim 26 further comprisingdeploying an occlusive balloon mounted near the distal end of theaspiration catheter to occlude carotid artery during aspiration.
 32. Themethod of claim 26 wherein the clot engagement device allows blood topass through.
 33. The method of claim 26 further comprising breaking theclot into fragments by pulling the aspiration catheter and the clotengagement device against each other during the aspiration.